The most dangerous class of abusers is the paranoid-delusional. If your ex is one of these, he is likely to:
Believe that you still love him (erotomania). Interpret everything you do or say -- even to third parties -- as "hidden messages" addressed to him and professing your undying devotion (ideas of reference).
Confuse the physical with the emotional (regard sex as "proof" of love and be prone to rape you).
Blame the failure of the relationship on you or on others -- social workers, your friends, your family, your children.
Seek to "remove" the obstacles to a "happy" and long relationship -- sometimes by resorting to violence (kidnapping or murdering the sources of frustration).
Be very envious of your newfound autonomy and try to sabotage it by reasserting his control over you (for instance, break and enter into your house, leave intrusive messages on your answering machine, follow you around and monitor your home from a stationary car).
Harm you (and sometimes himself) in a fit of indignation (and to punish you) if he feels that no renewed relationship is possible.
Develop persecutory delusions. Perceive slights and insults where none are intended. Become convinced that he is the centre of a conspiracy to deny him (and you) happiness, to humiliate him, punish him, delude him, impoverish him, confine him physically or intellectually, censor him, impose on his time, force him to action (or to inaction), frighten him, coerce him, surround and besiege him, change his mind, part with his values, victimise or even murder him, and so on.
(From the book "Malignant Self-love: Narcissism Revisited" by Sam Vaknin - Click on this link to purchase: http://www.narcissistic-abuse.com/thebook.html)